// base64加密开始
var keyStr = "ABCDEFGHIJKLMNOP" + "QRSTUVWXYZabcdef" + "ghijklmnopqrstuv"
                + "wxyz0123456789+/" + "=";

function encode64(input) {
        var output = "";
        var chr1, chr2, chr3 = "";
        var enc1, enc2, enc3, enc4 = "";
        var i = 0;
        do {
                chr1 = input.charCodeAt(i++);
                chr2 = input.charCodeAt(i++);
                chr3 = input.charCodeAt(i++);
                enc1 = chr1 >> 2;
                enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
                enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
                enc4 = chr3 & 63;
                if (isNaN(chr2)) {
                        enc3 = enc4 = 64;
                } else if (isNaN(chr3)) {
                        enc4 = 64;
                }
                output = output + keyStr.charAt(enc1) + keyStr.charAt(enc2)
                                + keyStr.charAt(enc3) + keyStr.charAt(enc4);
                chr1 = chr2 = chr3 = "";
                enc1 = enc2 = enc3 = enc4 = "";
        } while (i < input.length);

        return output;
}
// base64加密结束